I'll never forget (and always regret for not having photographed) a postcard picturing a skeleton at the bus stop, with the underlying caption: Dublin bus.
Having lived in Dublin for two years, I can say that postcard gets pretty well to the point. Some buses pass regularly, but others never come. The worst thing ever when you leave home in the morning and get to the stop, is seeing your bus leaving: you are going to be late.
Dublin city centre is quite walkable, but if you are to stay longer than a week, you can't miss visiting the villages around the outskirts, such as Howth, Malahide, Dun Laoghaire, and for a more comfortable tour, your best best is to go to a car hire in Dublin. By relying on pricey public transports, journeying through the towns around Dublin can take you days, instead, by driving you keep your own pace and visit much more.
Howth is a little fishing village that offers truly breathtaking views, and restaurants serve the best salmon in the area. On Sunday there is also a little openair market with stands selling homemade products, not only Irish: I found a delicious Polish bread with many cereals.
If you ever go to Howth, get fit before: you can't miss climbing the sheer cliff up to the tower, it's a great, properly thrilling stroll.
In Malahide, besides the lovely beaches, there is a beautiful castle, inhabited by the Talbot family for some eight centuries. If you have time and feel like driving, a very suggestive spot is definitely Glendalough.
I went to Glendalough by coach and I spent there a whole day. Truly amazing, the tour starts at an old cemetery, with a tiny old church that reminds me of the movie Magdalene's Sisters about the past Catholic zealotry of the Irish people.
Going beyond the graveyard, there is a countryside path with a river equipped with many bridges, two lakes, wildlife and seldom heritage sites, all contributing in giving the impression of a bucolic walk where modernity hasn't arrived yet.
Of course the dream suddenly stops when you get to the end of the itinerary and find yourself in front of fast-food stands releasing the smell of freshly made sandwiches.
The trip to Glendalough really impressed me, even if there's no museum or castle to visit, and I surely recommend it to anyone who plans a holiday in Dublin.